St Denys' Church, Walmgate, York
14th-Century Glass: Conservation and Environmental Protection of
Four North Nave Aisle Windows
The Parish Church of St Denys is a Grade I listed building dating back to the 12th century. The North aisle was rebuilt in the 14th century as a chapel for the wealthy and powerful Percy family, the Earls of Northumberland. By the early 21st century however, alarming cracks were beginning to open up in the West wall, showing that the aisle was pulling away from the rest of the building.
The major HLF-assisted restoration project of 2017-18 was driven by the need to stabilise and underpin the stonework, but also provided the perfect opportunity to conserve and protect the important medieval stained glass.
Barley Studio were pleased to work alongside main contractor Geoff Neal Roofing and Matthias Garn Master Mason and Partner, as their skilled teams stabilised and re-built the stonework.
The three windows of the North wall originally formed an ensemble of the same date (ca. 1340) and by the same maker, although the westernmost now contains stained glass from an early 13th-century lancet, probably the earliest stained glass surviving in the city of York.
These windows had been sympathetically restored by JW Knowles in the late 19th century, and were found to be generally in good condition. The glass was carefully cleaned and some aesthetic improvements made through reducing the visual intrusion of previous mending leads.
The East window of the North aisle, which also dates to the mid-14th century, is now very fragmented but originally depicted a ‘Jesse tree’. Left unprotected over nearly seven centuries, many pieces of the original medieval glass had corroded to such an extent that they had crumbled away, leaving open holes. We had no option but to replace these pieces with new glass, stippled to tone in with surrounding areas. Previous unpainted repairs were toned down by stippling with cold paint, again to tone in with the surviving historic glass.
Some of the tracery openings also contained fragments of medieval glass in a somewhat haphazard ‘jigsaw’ arrangement. As the remaining tracery openings contained clear diamond quarry glazing of the nineteenth and twentieth centuries, we proposed to make a new arrangement of the medieval fragments into the lowest panels of the main lights, while completing the tracery in diamond quarries, returning symmetry to the overall appearance of the window.
Most importantly, all of the windows were reinstalled into the restored stonework with the benefit of internally ventilated environmental protective glazing. A new outer glazing layer was produced in clear glass with minimal lead lines, following the main design lines of the stained glass, to give a sympathetic appearance to the exterior and to match the protective glazing previously installed by Barley Studio to two South aisle windows. This environmental protection, along with the mechanical protection given by wire guards, will ensure that this beautiful and highly significant ensemble of medieval stained glass is preserved for future generations to enjoy.
